Need help with the computer.I think.

Ok. Ive had this car for like 4 years now. In the course of that time ive replaced the alternator the fuel pump filters etc the clutch plates etc as well as a 02 sensor. Had a new batter put on. That went along with my alternator issues.

well all of a sudden id be driving and out of no where it would just shut off. All the inside lights engine batter etc would come on and I couldnt get it to start again. Id wait 10.15.30 minutes it would start up long enought to get me hiome and would die. Again. It did this over and over and over again. So we thought fuel issues. Or pump had those replaced. Alternator checked etc. And to no avail it didint solve my issue. My cousin had been fooling around with some amp wires. So now were thinking he fried the computer and it shuts off when it gets too hot.
i have a computer that works to put on it. But I wanted a few more opinions about what it could possibley be. Im at the end of my rope. And if anyone could tell me the current location of the computer. Im a severly non car sense female sad to say but im about tired of trying what everyone else says and it getting me no where.I love this car and would love for it to be up and running again. Thanks in advance